Goto Section: 11.21 | 11.32 | Table of Contents

FCC 11.31
Revised as of September 1, 2021
Goto Year:2020 | 2022
  §  11.31   EAS protocol.

   (a) The EAS uses a four part message for an emergency activation of the
   EAS. The four parts are: Preamble and EAS Header Codes; audio Attention
   Signal; message; and, Preamble and EAS End Of Message (EOM) Codes.

   (1) The Preamble and EAS Codes must use Audio Frequency Shift Keying at
   a rate of 520.83 bits per second to transmit the codes. Mark frequency
   is 2083.3 Hz and space frequency is 1562.5 Hz. Mark and space time must
   be 1.92 milliseconds. Characters are ASCII seven bit characters as
   defined in ANSI X3.4-1977 ending with an eighth null bit (either 0 or
   1) to constitute a full eight-bit byte.

   (2) The Attention Signal must be made up of the fundamental frequencies
   of 853 and 960 Hz. The two tones must be transmitted simultaneously.
   The Attention Signal must be transmitted after the EAS header codes.

   (3) The message may be audio, video or text.

   (b) The ASCII dash and plus symbols are required and may not be used
   for any other purpose. Unused characters must be ASCII space
   characters. FM or TV call signs must use a slash ASCII character number
   47 (/) in lieu of a dash.

   (c) The EAS protocol, including any codes, must not be amended,
   extended or abridged without FCC authorization. The EAS protocol and
   message format are specified in the following representation.

   Examples are provided in FCC Public Notices.



   second pause)

   (transmission of 8 to 25 seconds of Attention Signal)

   (transmission of audio, video or text messages)

   (at least a one second pause)

   [PREAMBLE]NNNN (one second pause)

   [PREAMBLE]NNNN (one second pause)

   [PREAMBLE]NNNN (at least one second pause)

   [PREAMBLE] This is a consecutive string of bits (sixteen bytes of AB
   hexadecimal [8 bit byte 10101011]) sent to clear the system, set AGC
   and set asynchronous decoder clocking cycles. The preamble must be
   transmitted before each header and End of Message code.

   ZCZC—This is the identifier, sent as ASCII characters ZCZC to indicate
   the start of ASCII code.

   ORG—This is the Originator code and indicates who originally initiated
   the activation of the EAS. These codes are specified in paragraph (d)
   of this section.

   EEE—This is the Event code and indicates the nature of the EAS
   activation. The codes are specified in paragraph (e) of this section.
   The Event codes must be compatible with the codes used by the NWS
   Weather Radio Specific Area Message Encoder (WRSAME).

   PSSCCC—This is the Location code and indicates the geographic area
   affected by the EAS alert. There may be 31 Location codes in an EAS
   alert. The Location code uses the codes described in the American
   National Standards Institute (ANSI) standard, ANSI INCITS 31-2009
   (“Information technology—Codes for the Identification of Counties and
   Equivalent Areas of the United States, Puerto Rico, and the Insular
   Areas”). Each state is assigned an SS number as specified in paragraph
   (f) of this section. Each county and some cities are assigned a CCC
   number. A CCC number of 000 refers to an entire State or Territory. P
   defines county subdivisions as follows: 0 = all or an unspecified
   portion of a county, 1 = Northwest, 2 = North, 3 = Northeast, 4 = West,
   5 = Central, 6 = East, 7 = Southwest, 8 = South, 9 = Southeast. Other
   numbers may be designated later for special applications. The use of
   county subdivisions will probably be rare and generally for oddly
   shaped or unusually large counties. Any subdivisions must be defined
   and agreed to by the local officials prior to use.

   + TTTT—This indicates the valid time period of a message in 15 minute
   segments up to one hour and then in 30 minute segments beyond one hour;
   i.e., + 0015, + 0030, + 0045, + 0100, + 0430 and + 0600.

   JJJHHMM—This is the day in Julian Calendar days (JJJ) of the year and
   the time in hours and minutes (HHMM) when the message was initially
   released by the originator using 24 hour Universal Coordinated Time

   LLLLLLLL—This is the identification of the EAS Participant, NWS office,
   etc., transmitting or retransmitting the message. These codes will be
   automatically affixed to all outgoing messages by the EAS encoder.

   NNNN—This is the End of Message (EOM) code sent as a string of four
   ASCII N characters.

   (d) The only originator codes are:
          Originator          ORG code
   EAS Participant            EAS
   Civil authorities          CIV
   National Weather Service   WXR
   Primary Entry Point System PEP

   (e) The following Event (EEE) codes are presently authorized:
               Nature of activation              Event codes
   National Codes (Required):
   Emergency Action Notification (National only) EAN.
   National Information Center                   NIC
   National Periodic Test                        NPT.
   Required Monthly Test                         RMT.
   Required Weekly Test                          RWT.
   State and Local Codes (Optional):
   Administrative Message                        ADR.
   Avalanche Warning                             AVW.
   Avalanche Watch                               AVA.
   Blizzard Warning                              BZW.
   Blue Alert                                    BLU.
   Child Abduction Emergency                     CAE.
   Civil Danger Warning                          CDW.
   Civil Emergency Message                       CEM.
   Coastal Flood Warning                         CFW.
   Coastal Flood Watch                           CFA.
   Dust Storm Warning                            DSW.
   Earthquake Warning                            EQW.
   Evacuation Immediate                          EVI.
   Extreme Wind Warning                          EWW.
   Fire Warning                                  FRW.
   Flash Flood Warning                           FFW.
   Flash Flood Watch                             FFA.
   Flash Flood Statement                         FFS.
   Flood Warning                                 FLW.
   Flood Watch                                   FLA.
   Flood Statement                               FLS.
   Hazardous Materials Warning                   HMW.
   High Wind Warning                             HWW.
   High Wind Watch                               HWA.
   Hurricane Warning                             HUW.
   Hurricane Watch                               HUA.
   Hurricane Statement                           HLS.
   Law Enforcement Warning                       LEW.
   Local Area Emergency                          LAE.
   Network Message Notification                  NMN.
   911 Telephone Outage Emergency                TOE.
   Nuclear Power Plant Warning                   NUW.
   Practice/Demo Warning                         DMO.
   Radiological Hazard Warning                   RHW.
   Severe Thunderstorm Warning                   SVR.
   Severe Thunderstorm Watch                     SVA.
   Severe Weather Statement                      SVS.
   Shelter in Place Warning                      SPW
   Special Marine Warning                        SMW.
   Special Weather Statement                     SPS.
   Storm Surge Watch                             SSA.
   Storm Surge Warning                           SSW.
   Tornado Warning                               TOR.
   Tornado Watch                                 TOA.
   Tropical Storm Warning                        TRW.
   Tropical Storm Watch                          TRA.
   Tsunami Warning                               TSW.
   Tsunami Watch                                 TSA.
   Volcano Warning                               VOW.
   Winter Storm Warning                          WSW.
   Winter Storm Watch                            WSA.

   (f) The All U.S., State, Territory and Offshore (Marine Area) ANSI
   number codes (SS) are as follows. County ANSI numbers (CCC) are
   contained in the State EAS Mapbook.
       ANSI No.
   All U.S 00
   AL 01
   AK 02
   AZ 04
   AR 05
   CA 06
   CO 08
   CT 09
   DE 10
   DC 11
   FL 12
   GA 13
   HI 15
   ID 16
   IL 17
   IN 18
   IA 19
   KS 20
   KY 21
   LA 22
   ME 23
   MD 24
   MA 25
   MI 26
   MN 27
   MS 28
   MO 29
   MT 30
   NE 31
   NV 32
   NH 33
   NJ 34
   NM 35
   NY 36
   NC 37
   ND 38
   OH 39
   OK 40
   OR 41
   PA 42
   RI 44
   SC 45
   SD 46
   TN 47
   TX 48
   UT 49
   VT 50
   VA 51
   WA 53
   WV 54
   WI 55
   WY 56
   AS 60
   FM 64
   GU 66
   MH 68
   PR 72
   PW 70
   UM 74
   VI 78
   Offshore (Marine Areas)^1
   Eastern North Pacific Ocean, and along U.S. West Coast from Canadian
   border to Mexican border 57
   North Pacific Ocean near Alaska, and along Alaska coastline, including
   the Bering Sea and the Gulf of Alaska 58
   Central Pacific Ocean, including Hawaiian waters 59
   South Central Pacific Ocean, including American Samoa waters 61
   Western Pacific Ocean, including Mariana Island waters 65
   Western North Atlantic Ocean, and along U.S. East Coast, from Canadian
   border south to Currituck Beach Light, N.C 73
   Western North Atlantic Ocean, and along U.S. East Coast, south of
   Currituck Beach Light, NC, following the coastline to Ocean Reef, FL,
   including the Caribbean 75
   Gulf of Mexico, and along the U.S. Gulf Coast from the Mexican border
   to Ocean Reef, FL 77
   Lake Superior 91
   Lake Michigan 92
   Lake Huron 93
   Lake St. Clair 94
   Lake Erie 96
   Lake Ontario 97
   St. Lawrence River above St. Regis 98

   ^1The numbers assigned to the offshore marine areas listed in this
   table are not described under the ANSI standard, but rather are numeric
   codes that were assigned by the National Weather Service.

   [ 59 FR 67092 , Dec. 28, 1994, as amended at  60 FR 55999 , Nov. 6, 1995;
    61 FR 54952 , Oct. 23, 1996;  63 FR 29663 , June 1, 1998;  67 FR 18508 ,
   Apr. 16, 2002;  67 FR 77174 , Dec. 17, 2002;  69 FR 72031 , Dec. 10, 2004;
    70 FR 71033 , Nov. 25, 2005;  77 FR 16701 , Mar. 22, 2012;  80 FR 37174 ,
   June 30, 2015;  81 FR 53043 , Aug. 11, 2016;  83 FR 2563 , Jan. 18, 2018]


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Goto Year: 2020 | 2022
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